Do not render dialog where it overflows screen

Author: tompng

lib/reline/line_editor.rb

@@ -714,6 +714,9 @@ def add_dialog_proc(name, p, context = nil)
 
     Reline::IOGate.hide_cursor
     ymin, ymax = (ranges_to_restore.keys + new_dialog_ranges.keys).minmax
+    screen_y_range = (@scroll_partial_screen || 0)..(@scroll_partial_screen || 0) + @screen_height - 1
+    ymin = ymin.clamp(screen_y_range.begin, screen_y_range.end)
+    ymax = ymax.clamp(screen_y_range.begin, screen_y_range.end)
     dialog_y = @first_line_started_from + @started_from
     cursor_y = dialog_y
     scroll_down(ymax - cursor_y)

test/reline/yamatanooroti/test_rendering.rb

@@ -1319,12 +1319,12 @@ def test_scroll_at_bottom_for_dialog
         prompt>
         prompt>
         prompt>
+        prompt>   S
         prompt>   String
         prompt>   Struct
-        prompt>   Symbol
-        prompt> enScriptError
+        prompt> enSymbol
+                  ScriptError
                   SyntaxError
-                  Signal
       EOC
     end